// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ipc/ipc_platform_file.h"
#include "build/build_config.h"

#if defined(OS_POSIX)
#include <unistd.h>
#endif

namespace IPC {

PlatformFileForTransit GetFileHandleForProcess(base::PlatformFile handle,
    base::ProcessHandle process,
    bool close_source_handle)
{
    IPC::PlatformFileForTransit out_handle;
#if defined(OS_WIN)
    DWORD options = DUPLICATE_SAME_ACCESS;
    if (close_source_handle)
        options |= DUPLICATE_CLOSE_SOURCE;
    if (handle == INVALID_HANDLE_VALUE || !::DuplicateHandle(::GetCurrentProcess(), handle, process, &out_handle, 0, FALSE, options)) {
        out_handle = IPC::InvalidPlatformFileForTransit();
    }
#elif defined(OS_POSIX)
    // If asked to close the source, we can simply re-use the source fd instead of
    // dup()ing and close()ing.
    // When we're not closing the source, we need to duplicate the handle and take
    // ownership of that. The reason is that this function is often used to
    // generate IPC messages, and the handle must remain valid until it's sent to
    // the other process from the I/O thread. Without the dup, calling code might
    // close the source handle before the message is sent, creating a race
    // condition.
    int fd = close_source_handle ? handle : ::dup(handle);
    out_handle = base::FileDescriptor(fd, true);
#else
#error Not implemented.
#endif
    return out_handle;
}

PlatformFileForTransit TakeFileHandleForProcess(base::File file,
    base::ProcessHandle process)
{
    return GetFileHandleForProcess(file.TakePlatformFile(), process, true);
}

} // namespace IPC
